This project is designed to study the comparative dynamics of benzo(a)pyrene metabolism in human and rodent cells and tissues. The qualitative similarity of B(a)P metabolites in both resistant and susceptible species suggest the critical steps in determining the carcinogenicity of PAH's may be a function of the rate metabolism and the mode of overall processing of the carcinogen. A series of time course studies will be performed in which the complete metabolic processing of B(a)P will be determined. This will include qualitative and quantitative analysis of intra-and extracellular metabolites and of binding to nucleic acids and proteins. Emphasis will be placed upon understanding the role detoxifying conjugation reactions play in the removal of the reactive electrophiles and their immediate precursors, since this is a major detoxifying step in vivo.